Question

When I want to scale Canvas with background it don’t work the way I want. The background is the same and only content of Canvas is scaling. But if I change Canvas to InkCanvas it work good but because InkCanvas don’t support MouseLeftButtonDown event I have to use Canvas.

It’s my code

 <ScrollViewer Grid.Column="1" HorizontalScrollBarVisibility="Visible">
        <Canvas x:Name="CanvasChart" MouseMove="CanvasChart_MouseMove" MouseLeave="CanvasChart_MouseLeave"  
                   Grid.Column="1" Margin="20 20 20 20">
            <Canvas.Background >
                <ImageBrush Stretch="UniformToFill"  ImageSource="D:\Praca\JanarMapy\JanarMapy\Maps\Montenegro_Map.png"></ImageBrush>
            </Canvas.Background>
            <Canvas.LayoutTransform>
                <ScaleTransform 
                                ScaleX="{Binding Path=Value, ElementName=zoomSlider}"
                                ScaleY="{Binding Path=Value, ElementName=zoomSlider}"/>
            </Canvas.LayoutTransform>
        </Canvas>
    </ScrollViewer>

Answer 1

At first you would have to disable automatic stretching of the background ImageBrush to see any scaling effect:

<ImageBrush Stretch="None" ... />

But note that a brush does not participate in layout calculations. If your intention is to resize the content of the ScrollViewer by a scaling transform you should consider the following solution, in which the Grid will always have at least the size of the Image.

<ScrollViewer Grid.Column="1" HorizontalScrollBarVisibility="Visible" VerticalScrollBarVisibility="Visible">
    <Grid Margin="20 20 20 20">
        <Grid.LayoutTransform>
            <ScaleTransform ScaleX="{Binding Path=Value, ElementName=zoomSlider}" 
                            ScaleY="{Binding Path=Value, ElementName=zoomSlider}"/>
        </Grid.LayoutTransform>
        <Image Source="D:\Praca\JanarMapy\JanarMapy\Maps\Montenegro_Map.png"
               Stretch="None"/>
        <Canvas x:Name="CanvasChart"/>
    </Grid>
</ScrollViewer>

As an alternative that works in a similar way as with InkCanvas you could set a fixed size for the Canvas:

<ScrollViewer Grid.Column="1" HorizontalScrollBarVisibility="Visible" VerticalScrollBarVisibility="Visible">
    <Canvas x:Name="CanvasChart" Margin="20 20 20 20"
            Width="500" Height="400">
        <Canvas.Background >
            <ImageBrush Stretch="UniformToFill" ImageSource="D:\Praca\JanarMapy\JanarMapy\Maps\Montenegro_Map.png"/>
        </Canvas.Background>
        <Canvas.LayoutTransform>
            <ScaleTransform ScaleX="{Binding Path=Value, ElementName=zoomSlider}" 
                            ScaleY="{Binding Path=Value, ElementName=zoomSlider}"/>
        </Canvas.LayoutTransform>
    </Canvas>
</ScrollViewer>